/**
 *
 *    geo-platform
 *    Rich webgis framework
 *    http://geo-platform.org
 *   ====================================================================
 *
 *   Copyright (C) 2008-2021 geoSDI Group (CNR IMAA - Potenza - ITALY).
 *
 *   This program is free software: you can redistribute it and/or modify it
 *   under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version. This program is distributed in the
 *   hope that it will be useful, but WITHOUT ANY WARRANTY; without
 *   even the implied warranty of MERCHANTABILITY or FITNESS FOR
 *   A PARTICULAR PURPOSE. See the GNU General Public License
 *   for more details. You should have received a copy of the GNU General
 *   Public License along with this program. If not, see http://www.gnu.org/licenses/
 *
 *   ====================================================================
 *
 *   Linking this library statically or dynamically with other modules is
 *   making a combined work based on this library. Thus, the terms and
 *   conditions of the GNU General Public License cover the whole combination.
 *
 *   As a special exception, the copyright holders of this library give you permission
 *   to link this library with independent modules to produce an executable, regardless
 *   of the license terms of these independent modules, and to copy and distribute
 *   the resulting executable under terms of your choice, provided that you also meet,
 *   for each linked independent module, the terms and conditions of the license of
 *   that module. An independent module is a module which is not derived from or
 *   based on this library. If you modify this library, you may extend this exception
 *   to your version of the library, but you are not obligated to do so. If you do not
 *   wish to do so, delete this exception statement from your version.
 */
package org.geosdi.geoplatform.rs.support.compression.provider;

import org.geosdi.geoplatform.rs.support.compression.annotation.GPCompress;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.Provider;
import javax.ws.rs.ext.WriterInterceptor;
import javax.ws.rs.ext.WriterInterceptorContext;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Optional;
import java.util.zip.GZIPOutputStream;

import static java.lang.Boolean.FALSE;
import static java.util.Arrays.stream;

/**
 * @author Giuseppe La Scaleia - CNR IMAA geoSDI Group
 * @email giuseppe.lascaleia@geosdi.org
 */
@Provider
@GPCompress
public class GPGZIPWriterInterceptor implements WriterInterceptor {

    private static final Logger logger = LoggerFactory.getLogger(GPGZIPWriterInterceptor.class);

    /**
     * Interceptor method wrapping calls to {@link javax.ws.rs.ext.MessageBodyWriter#writeTo} method.
     * The parameters of the wrapped method called are available from {@code context}.
     * Implementations of this method SHOULD explicitly call
     * {@link WriterInterceptorContext#proceed} to invoke the next interceptor in the chain,
     * and ultimately the wrapped {@code MessageBodyWriter.writeTo} method.
     *
     * @param context invocation context.
     * @throws IOException             if an IO error arises or is thrown by the wrapped
     *                                 {@code MessageBodyWriter.writeTo} method.
     * @throws WebApplicationException thrown by the wrapped {@code MessageBodyWriter.writeTo} method.
     */
    @Override
    public void aroundWriteTo(WriterInterceptorContext context) throws IOException, WebApplicationException {
        Optional<GPCompress> value = stream(context.getAnnotations())
                .filter(a -> (a instanceof GPCompress))
                .map(a -> (GPCompress) a)
                .findFirst();
        int threshold = ((value != null) && !(value.equals(Optional.empty())) ? value.get().thrushold() : 512);
        boolean syncFlush = ((value != null) && !(value.equals(Optional.empty())) ? value.get().syncFlush() : FALSE);
        logger.trace("############################Threshold : {} - SyncFlush : {}\n", threshold, syncFlush);
        MultivaluedMap<String, Object> headers = context.getHeaders();
        headers.add("Content-Encoding", "gzip");
        OutputStream outputStream = context.getOutputStream();
        context.setOutputStream(new GZIPOutputStream(outputStream, threshold));
        context.proceed();
    }
}